That's an interesting article, although the level of hype for cloud computing is rather high (and I'm an enormous fan of cloud computing): "When PCs and client/server computing came along, the departmental computing guys (i.e. DEC), considered PCs to be a special case of smart terminals... So the batchguys are dead, the timesharing guys are dead, the departmental computing guys are dead, and the client server guys are dead. Notice a pattern?"
That said, there are already several hybrid memory/disk storage layers that might actually be a better choice than the pure in-memory approach that the author suggests. For example, MongoDB is basically an in-memory document database that's mmapped to a disk file and flushed once per minute. CouchDB, IIRC, is basically an in-memory database backed by an append-only transaction log on disk. These sorts of designs should give you many of the bandwidth advantages of pure memory systems, but still maintain the ability to survive a power outage.